Detection of defects in a moving web of material

ABSTRACT

A system is provided for controlling movement of a web of material relative to a work station in which defective areas are removed and the web is then spliced to provide continuity. The web of material has patterns of magnetic ink printed on one surface in spaced, parallel arrays both transversely and longitudinally of the web. Each pattern is formed with zones of ink such that the pattern will produce a series of pulses when magnetically saturated and moved relative to a transducer. An area surrounding a defect in the other surface of the web is magnetically saturated and, when detected, serves to produce the series of pulses which, in turn, produce a control pulse that regulates movement of the web of material relative to the work station so as to position the detected area in the station.

United States Patent [191 Kachioff et al.

[451 Apr. 23, 1974 DETECTION OF DEFECTS IN A MOVING WEB OF MATERIAL Inventors: Yuval Kachioff; Howard R.

DeMallie, both of Rochester, N.Y.

Assignee: Eastman Kodak Company, Rochester, N.Y.

Filed: May 4, 1973 Appl. No.: 357,442

[52] US. Cl. .Q. 226/33, 226/49 [51] Int. Cl B65h 23/18 [58] Field of Search 226/33, 43, 49, 50, 51

[56] References Cited UNITED STATES PATENTS 3,572,565 3/1971 Steggall 226/33 3,696,981 10/1972 Levy 226/33 MAGNET/C PRINT/N6 DEGAWS/NG Primary Examinen-Richard A. Schacher Attorney, Agent, or Firm-Lloyd F. Seebach [5 7 ABSTRACT A system is provided for controlling movement of a web of material relative to a work station in which defective areas are removed and the web is then spliced to provide continuity. The web of material has patterns of magnetic ink printed on one surface in spaced, parallel arrays both transversely and longitudinally, of the web. Each pattern is formed with zones of ink such that the pattern will produce a series of pulses when magnetically saturated and moved relative to a transducer. An area surrounding a defect in the other surface of the web is magnetically saturated and, when detected, serves to produce the series of pulses which, in turn, produce a control pulse that regulates movement of the web of material relative to the work station so as to position the detected area in the station.

12 Claims, 6 Drawing Figures PATENTEIJAFR 23 4 I 3806x315 SHEET 1 [IF 2- III/Ill DETECTION OF DEFECTS IN A MOVING WEB OF MATERIAL FIELD OF THE INVENTION The invention relates to apparatus for controlling the movement of a web of material upon detection of a magnetically saturated area denoting a defect and, more particularly, to circuitry associated with the apparatus for controlling the movement of the web.

DESCRIPTION OF THE PRIOR ART In the detection of defects in a web of material, particularly electrically conductive material, such as a thin, continuous, metallic strip, it is known to utilize magnetic recording or magnetic saturation for denoting an area in which a defect has been detected. In a system such as that indicated in U. S. Pat. No. 2,937,368, an electrical signal is applied via a transducer extending transversely of a magnetic record medium that is being moved relative to a plurality of scanners which detect the flux pattern. Any variation in the flux pattern denotes a defect in the web. This signal, when picked up by a subsequent transducer, will cause the recording of a mark on the tape or web in the area corresponding to that in which the defect signal was picked up by the latter transducer.

In U. S. Pat. No. 2,904,l74, a system is disclosed in which a web of material having a photosensitive layer on one surface is moved past an inspection station in which the web is visually scanned by an operator to detect any defects in the photosensitive surface. Upon recognizing a defect, the operator actuates one or more of several keys corresponding approximately to the lateral position of the defect relative to thewidth of the web and through the medium of the key, a large spot of magnetic ink is applied to the web in the approximate location of the defect. The web is then slit longitudinally and cut transversely into sheets. Upon further inspection, those sheets bearing a marking of magnetic ink are rejected because of the indicated defect.

In both of the foregoing systems, the detecting and marking of a defect can be unwarranted because the size or condition of the defect is such that there should be no rejection of the material. For example, in the latter disclosure, inadvertent actuation of one of the keys can result in the application of a small amount of magnetic ink to the material without a defect actually being in that particular area. Also, the drying of the ink presents a problem in that if it has not dried thoroughly, there is the possibility that it would or could transfer to another area of the web upon wind-up. Depending on the web path, the ink could also transfer to the surface of a roll in which case the ink would transfer at regularly, spaced intervals to the web with decreasing density. With visual inspection, there is always the possibility that the operator or insepctor may tend to err in the direction of denoting a defect, if there is any question, rather than permit the defect to pass. It should be readily appreciated, therefore, that a system which will recognize and pass defects of a predetermined magnitude will produce not only a saving as to the material per se but also as to the cost for actual inspection and detection. With systems in which the marking is accomplished as described above or by punching holes in the web in the area of the defect, the movement of the web must be slowed down, upon detecting a defect, in order to permit the marking device to operate. [n.the case of punching holes, the web is slowed down from 1,000 feet per minute to about 50 feet per minute.

SUMMARY OF THE INVENTION It is an object of the invention to provide a system for controlling the movement of a web of material, upon detection of a defect, whereby only defects of a predetermined magnitude result in rejection of the portion of the material in which the defect is detected.

Another object of the invention is to provide a system for controlling the movement of a web of dielectric material in which a series of pulses derived from a magnetically saturated area requires a predetermined number of the pulses to be transmitted into a storage means before a control pulse is produced for stopping and reversing movement of the web of material.

Yet another object of the invention is to provide a system for controlling movement of a web of dielectric material, upon detection of a defect, in which stoppage and reverse movement of the web is controlled by a series of pulses derived from magnetically saturated zones in the area containing the defect.

These and other objects and advantages of the invention will be apparent to those skilled in the art by the description which follows.

The objects of the invention are attained from patterns of magnetic ink that are printed on a surface of the web of material, one or more of the patterns being magnetically saturated in an area in which a defect is detected. A series of pulses are derived from the patterns that have been magnetically saturated to denote the defect. In a preferred embodiment of the invention, the webof material comprises a support having a photosensitive layer on one surface thereof and patterns of magnetic ink printed on the other surface. The patterns are printed in spaced relation both longitudinally and transversely of the material. Each pattern is designed so as to provide a number of zones of magnetic ink, when scanned in a direction corresponding to movement of the web. Upon detection of a defect, an area of the material in which the defect appears is magnetically saturated through the medium of the pattern or patterns in accordance with the extent of the defect in a longitudinal and/or transverse direction. After the web of material has been cut into strips and rewound into rolls, each strip is then moved past a detection station in which the defects are sensed. With the detection of each defect, the material is brought to a stop and then reversed in its direction of movement in order to position the defect with respect to a work station. The distance that the defect is moved past the work station, after detection, is measured and, upon reversal of the direction of movement of the web, the measured distance is used to position the area containing the defect in the work station. This area is removed from the strip of material and the strip is spliced together to maintain continuity. If the strip had been previously cut into sheets, the discrete sheets could be sorted as disclosed in U. S. Pat. No. 2,904,174 noted above.

DESCRIPTION OF THE DRAWINGS Reference is made to the drawings wherein like reference numerals and characters designate like parts and wherein:

FIGS. l-3 are enlarged cross-sections of a material, particularly a photosensitive material showing various arrangements of the support, photosensitive layer and printed patterns;

FIG. 4 is an enlarged plan view of a piece of a web showing a magnetic stripe along an edge and patterns of magnetic ink arranged transversely and longitudinally of the web of material in generally spaced and parallel configuration.

FIG. 5 is a schematic elevational view of a continuous system forprinting and coating asupport to produce a photosensitive material and for inspecting the same to detect any surface defects; and

FIG. 6 is a schematic view with schematic electrical circuitry forming a part thereof and showing the correlation of the circuitry with inspection of the strip of material that has been cut or slit from a web of material, as shown in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT In a preferred embodiment of the invention, a web 10 of material can comprise a support 11 of dielectric material, such as paper, a photographic film support, a thin, plastic material, etc., having a surface 12 on which a plurality of patterns 13 are printed with magnetic ink. The cross-section of various forms of the web 10 is shown in detail in FIGS. 1-3. In its simplest form, as shown in FIG. 1, the patterns 13 are printed on the surface 12 of a paper support 11. In FIG. 2, the same support 11 can be used with the patterns 13; but in this embodiment, a photosensitive layer 14 is coated on the other surface 15 of the paper support 11. In FIG. 3, another variation is disclosed in which the patterns 13 and the surface 15 are first coated with a layer 16 of a plastic material, such as polyethylene. The photosensitive layer 14 is then coated on the layer 16 which overlies surface 15. The invention can be applied to the detection of defects in a surface or surfaces of any one of the types of web formats described hereinabove. Also, the web 10 of material need not be limited to a dielectric material or support. Any support material can be used on which patterns of magnetic ink can be printed and which will permit the patterns to be magnetically saturated.

The patterns 13 of magnetic ink can be printed matter, such as a water mark, a particular design, a series of parallel, broken lines, a dot array, etc. However, it is essential that each pattern comprises a number of zones of magnetic ink that extend transversely of the web 10 of material, whereby magnetically saturating the pattern, upon detection of a'defect, will permit a number of pulses to be provided by these patterns as the web 10 is scanned to detect any defects. As shown in FIG. 4, the web 10 can be provided along one or both edges with a stripe 17 of magnetic material which can be utilized for recording web footage, index marks, inventory data, etc. The recording of such information can be effected before any further manufacting steps are taken with respect to printing, coating, slitting, etc.

nitude can be effectively designated by a corresponding small or large magnetically saturated area 19 as designated by the spaced horizontal lines.

The description which follows relates to the preparation of a web 10 of material by means of a continuous process. It should be understood that such a process can also be accomplished in a number of individual steps, whereby with accomplishment of each step, the web 10 is taken up in the form of a roll for use in the following or next step of manufacture. Again, the system is directed to the detection of defects in the surface of a web of photosensitive material but can be utilized with respect to any web of dielectric or other material capable of having magnetic patterns printed thereon that can be magnetically saturated.

In FIG. 5, the paper 11 is drawn from a roll of paper 20 by a set of rolls 21, one of which is driven by a motor 22 and is moved between print rolls 23 and 24. A magnetic ink 25 is contained in a receptacle 26 and is applied to paper 1 1 via a transfer roll 27 and the print roll 24. The print roll 24 has a design on its peripheral surface as described above for transferring the magnetic ink in a pattern from the roll 27 to the facing surface of the web of paper. The roll 23 is a pressure roll for maintaining the web in contact with the printing roll 24. The rolls 23 and 24 can be set up as discrete rolls for printing each-longitudinal array at patterns 13, or can each be a single roll extending transversely of the paper 11. In the latter case, roll 24 will carry a number of patterns that are arranged so as to produce an array as shown in .FIG. 4. The paper 11 is then moved through a drier 28'for setting the magnetic ink pattern by the roll 29 that is driven by a motor 30 in synchronism with the set of rolls 21. The paper 11 is then moved in a path defined by rolls 31, 32 and 33 to form a loop 34 which terminates. in a receptacle 35 containing a liquid, plastic material 36, such as polyethylene. On moving through the polyethylene, both surfaces 12 and 15 of the paper are coated with a thin layer 16 of the polyethylene, the magnetic patterns 13 on the surface 12 also being overcoated.

After the layer 16 of polyethylene has been applied, the paper is moved through a drier 38 in which various solvents are removed from the layer, thereby setting the polyethylene. The paper 11 is then moved over rolls 39 and 40 and with respect to a coating hopper 41 which applies the light sensitive layer 14 on the layer 16 relative to the surface 15 of the paper 11.

Before having the light sensitive layer 14 applied, the polyethylene coated paper 11 is moved relative to a group of permanent magnets 37 arranged in spaced, axial relation to roll 40. Any magnetism that might be imparted to the paper by the magnetic ink is removed by magnets 37. This'degaussing step is necessary in order to eliminate the possibility that such residual magnetism will generate false signals that later in the process will be interpreted as a defect in the surface of the web.

The paper 11 is now moved by rolls 42 and 43, the latter being driven by a motor 44. The paper moves through a scanning station 45 and then a write station 46, after which it is slit by rotary knives 47 and 48. In the scanning station 45, a beam of light from a laser 49 is scanned across the width of the paper by an oscillatable mirror 50. The light reflected from the surface of the paper 11 is incident on a group of photosensitive detectors 51 arranged transversely of the paper. Any defect in the surface or layer 16 of light sensitive material, such as a bubble, a streak, a mark or glob of light sensitive material, an uncoated area, etc. results in a different light level being reflected to certain of the photocells 51. Such a change in light level will cause one or more of photocells 51 to generate a signal indicative of the detected defect. Inasmuch as the photocells 51 are arranged transversely of the paper 11, one or more can be affected in accordance with the size of the defect. The photocells, detectors or sensors 51 are interconnected to a computer52 which processes the location of the defect relative to the width of the paper, the rate of movement of the paper and length of the defect. In addition, the signal generated by the defect through the computer 52 provides a signal to a tachometer 53 and, after an interval corresponding to the time and distance required for placing the defect relative to a transducer or write head 53 the computer 52 has determined the X-Y location as well as extent of the defect in both of these directions. At the time the defect approaches transducer 54, a signal is derived from the computer 52 which causes energization of one or more of transducers 54, thereby causing the pattern or patterns 12 being moved past the transducer to be magnetically saturated. The pattern or patterns that are so saturated will be located in an X-Y direction in accordance with the photocells initiated by the defect. The transducer 54 comprises one or more that are spaced transversely ofthe paper 11 in accordance with the transverse spacing at the patterns 12. A saturated area is larger than the defect and the extension in both directions, that is, transversely and longitudinally is controlled by computer 52. The slitting knives 47 and 48 are spaced transversely of the paper in accordance with the width of the strips into which the paper is to be slit. The individual strips are then wound up separately on take-up rolls 55, 56 and 57 by a drive means generally indicated as a motor 58.

After the defects have been marked and the paper slit into strips, a strip in roll form is then arranged for inspection, detection and removal of the defects, as shown in FIG. 6. The strip of material, now designated by the numeral 60, is moved from the supply roll 59 over a group of rolls 61, 62 and 63 to a take-up roll 64 driven by a motor 65. A transducer 70 is arranged relative to the roll 61 and spaced from the surface of the strip 60 being moved thereover. Between rolls 62 and 63, the strip is moved through a work station, designated by the numeral 71, in which the strip can be cut by a knife 72 to remove the defect and splice the strip so as to again form a continuous strip.

The movement of the strip is at a relatively high rate, for example, 1,000 feet/minute; and, consequently, the strip cannot be brought to an immediate stop upon detection of the area in which a defect is indicated. As a result, the strip is gradually brought to a stop with the area generally moving past and beyond the work station 71 and toward the take-up roll 64. Therefore, in order to remove the defect from the strip, it is necessary to reverse the direction of movement of the strip in order that the defect can be positioned in the work station for removal of the defective portion and splicing of the strip.

It is in connection with the aforementioned control that the following circuitry based on the detection of a defect will brake the movement of the strip of material, reverse the direction of motor 65, and position the defeet in the work station 71 relative to the knife 72.

The transducer 70 is one of several arranged transversely of the strip of material and relative to each array of longitudinal patterns spaced transversely of the strip in the same manner as the transducers 54 in FIG. 5. A signal derived from a magnetically saturated area by any one of the transducers results in a series of pulses being produced by the magnetically saturated zones comprising each pattern. These pulses are transmitted to an amplifier 80. The same pulses are transmitted to a tachometer 81, the first of such pulses initiating the tachometer. The tachometer generates a voltage in accordance with the speed of the strip and this voltage is transmitted to an integrator 82. The voltage generated in the interval between detection of a defect and bringing the strip to a stop is a measure of the distance that the defect overshoots the transducer 70 before coming to a full stop.

The series of pulses transmitted to amplifier are in accordance with the zones of magnetic ink that have been magnetically saturated. A voltage discriminator circuit 83 controls the amplitude of the pulses and these pulses are stored in a storing means generally designated by the numeral 84 and released upon reaching an established amplitude as determined by a staircase generator 85. Upon release, the pulse of established voltage provides through trigger circuit 86, a control pulse which is transmitted to motor control circuit 83 for initiating the stopping of motor 65 and then reversing its direction of movement. The integrator 82 controls the reverse movement to position the defect relative to transducer 70. However, through motor control circuit 83 an additional bias is provided, whereby the motor 65 is maintained in an energized state until the defect is positioned relative to work station 71 and knife 72.

. The circuitry described thus far is disclosed and described in more detail in copending U. S. application, Ser. No. 357,443, filed May 4, 1973, in the name of Richard W. Scales. This circuitry includes a second channel, designated by the numeral 90, which picks up an environmental transient noise and cancels the same.

to eliminate false triggering when the same transient noise is also picked up by the transducer heads 70. In this way, a false count of the pulses derived from a magnetic pattern is not generated. It should'also be pointed out that the circuitry is not subject to initiation by any normal noise transients picked up by the transducer heads 70, such as dust, dirt and-other factors in connection with the strip of material per se. If less than a predetermined number of pulses are received by the staircase generator 85 within a predetermined time interval, such pulses are prejudged to be noise transients and, hence, are discarded so no actuation of the trigger circuit 86 can take place.

This invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

We claim:

1. A system for controlling the movement of a web of dielectric material upon detection of a magnetically saturated area denoting a defect in one surface of the web, each such area being at least a part of one of a number of patterns of magnetic ink on the other surface of the web, the patterns being spaced transversely and longitudinally of the web and in spaced, parallel relation one to the other, the improvement comprising:

means for selectively controlling the movement of the web of material in a forward and a reverse direction in a prescribed path and through a work station at a predetermined linear rate;

means arranged downstream from the work station and transversely of the direction of movement of the web for detecting a magnetically saturated area;

means responsive to the detecting means for generating from the area'a series of timing pulses at a frequency directly proportional to the linear rate of the web; and

means responsive to the timing pulses for generating a control pulse upon counting a predetermined number of the timing pulses to arrest movement of the web.

2. The system in accordance with claim 1 wherein the detecting means comprises at least one transducer positioned relative to the patterns of magnetic ink.

3. The system in accordance with claim 1 wherein the detecting means comprises a transducer positioned relative to and spaced'from'each transversely spaced pattern of magnetic ink.

4. The system in accordance with claim 1 wherein the generating means for the control pulse comprises means for storing the predetermined number of timing pulses and a trigger circuit responsive to the accumulative amplitude value of each timing pulse for producing the control pulse.

5. The system in accordance with claim 4 wherein the storing means includes a staircase voltage generator.

6. A system in accordance with claim 1 wherein each pattern comprises a plurality of spaced zones arranged so as to produce a series of pulses when magnetically saturated and moved relative to a transducer.

7. A system in accordance with claim 6 wherein each pattern comprises an array of spaced dots of magnetic ink for producing the series of pulses.

8. A system for controlling the movement of a web of dielectric material upon detection of a magnetically saturated area denoting a defect in one surface of the web, each such area being at least a part of one of a number of patterns of magnetic ink on the other surface of the web, the patterns being spaced transversely and longitudinally of the web and in spaced, parallel relation one to the other, the improvement comprising:

means for selectively controlling the movement of the web of material in a forward and a reverse direction in a prescribed path and through a work station at a predetermined linear rate;

means arranged downstream from the work station and transversely of the direction of movement of the web for detecting a magnetically saturated area; means responsive ,to the detecting means for generating from the area a series of timing pulses at a frequency directly proportional to the linear rate of the web; I

means responsive to the timing pulses for generating a control pulse upon counting a predetermined number of the timing pulses;

means responsive to the control pulse for initiating stoppage of the moving means and for generating a signal after measuring the distance the area is moved beyond the work station; and

means responsive to the signal for initiating the moving means to reverse the direction of movement of the web and to the measuring means for stopping the work station.

9. The system in accordance with claim 8 wherein the detecting means comprises at least one transducer posi: tioned relative to the patterns of magnetic ink.

10. The system in accordance with claim 8 wherein the detecting means comprises a transducer positioned relative to and spaced from each transverselyspaced pattern of magnetic ink.

' 11. The system in accordance with claim 8 wherein the generating means for the control pulse comprises means for storing the predetermined number of timing pulses and a trigger circuit responsive tothe accumulative amplitude value of each timing pulse for producing the control pulse.

12. The system in accordance with claim 11 wherein the storing means includes a staircase voltage generator. 

1. A system for controlling the movement of a web of dielectric material upon detection of a magnetically saturated area denoting a defect in one surface of the web, each such area being at least a part of one of a number of patterns of magnetic ink on the other surface of the web, the patterns being spaced transversely and longitudinally of the web and in spaced, parallel relation one to the other, the improvement comprising: means for selectively controlling the movement of the web of material in a forward and a reverse direction in a prescribed path and through a work station at a predetermined linear rate; means arranged downstream from the work station and transversely of the direction of movement of the web for detecting a magnetically saturated area; means responsive to the detecting means for generating from the area a series of timing pulses at a frequency directly proportional to the linear rate of the web; and means responsive to the timing pulses for generating a control pulse upon counting a predetermined number of the timing pulses to arrest movement of the web.
 2. The system in accordance with claim 1 wherein the detecting means comprises at least one transducer positioned relative to the patterns of magnetic ink.
 3. The system in accordance with claim 1 wherein the detecting means comprises a transducer positioned relative to and spaced from each transversely spaced pattern of magnetic ink.
 4. The system in accordance with claim 1 wherein the generating means for the control pulse comprises means for storing the predetermined number of timing pulses and a trigger circuit responsive to the accumulative amplitude value of each timing pulse for producing the control pulse.
 5. The system in accordance with claim 4 wherein the storing means includes a staircase voltage generator.
 6. A system in accordance with claim 1 wherein each pattern comprises a plurality of spaced zones arranged so as to produce a series of pulses when magnetically saturated and moved relative to a transducer.
 7. A system in accordance with claim 6 wherein each pattern comprises an array of spaced dots of magnetic ink for producing the series of pulses.
 8. A system for controlling the movement of a web of dielectric material upon detection of a magnetically saturated area denoting a defect in one surface of the web, each such area being at least a part of one of a number of patterns of magnetic ink on the other surface of the web, the patterns being spaced transversely and longitudinally of the web And in spaced, parallel relation one to the other, the improvement comprising: means for selectively controlling the movement of the web of material in a forward and a reverse direction in a prescribed path and through a work station at a predetermined linear rate; means arranged downstream from the work station and transversely of the direction of movement of the web for detecting a magnetically saturated area; means responsive to the detecting means for generating from the area a series of timing pulses at a frequency directly proportional to the linear rate of the web; means responsive to the timing pulses for generating a control pulse upon counting a predetermined number of the timing pulses; means responsive to the control pulse for initiating stoppage of the moving means and for generating a signal after measuring the distance the area is moved beyond the work station; and means responsive to the signal for initiating the moving means to reverse the direction of movement of the web and to the measuring means for stopping the work station.
 9. The system in accordance with claim 8 wherein the detecting means comprises at least one transducer positioned relative to the patterns of magnetic ink.
 10. The system in accordance with claim 8 wherein the detecting means comprises a transducer positioned relative to and spaced from each transversely spaced pattern of magnetic ink.
 11. The system in accordance with claim 8 wherein the generating means for the control pulse comprises means for storing the predetermined number of timing pulses and a trigger circuit responsive to the accumulative amplitude value of each timing pulse for producing the control pulse.
 12. The system in accordance with claim 11 wherein the storing means includes a staircase voltage generator. 